Cal. Wat. Code § 13805
If a county or city fails to adopt an ordinance establishing water well, cathodic protection well, and monitoring well construction, maintenance, abandonment, and destruction standards within 120 days of receipt of the regional board's report of its determination and those standards are necessary pursuant to Section 13802, or fails to adopt or modify those well standards in the manner determined as necessary by the regional board pursuant to Section 13804 within 90 days of receipt of the regional board's report, the regional board shall adopt standards for water well, cathodic protection well, and monitoring well construction, maintenance, abandonment, and destruction for the area. The regional board well standards shall take effect 30 days from the date of their adoption by the regional board and shall be enforced by the city or county and have the same force and effect as if adopted as a county or city ordinance.
Ca. Water Code § 13805